All animals must eat to survive. With predators always
on the lookout for a meal, prey must constantly avoid being eaten. Any adaptation
the prey uses adds to the chances of survival for the species. Some adaptations
are defense mechanisms which can give the prey an advantage against enemies.

Prey Defense Mechanisms
There are many ways animals avoid falling prey to a predator.

The first is very direct and comes naturally. Imagine you are a rabbit and you have just noticed a fox preparing to attack. What would be your initial response? Right, you'd run. Animals can use speed as a very effective means of escaping predators. Remember, you can't eat what you can't catch!.

A second defense mechanism is camouflage or protective coloration. One form, cryptic coloration, allows the animal to blend in with its environment to avoid being detected. It is important to note that predators also use cryptic coloration to avoid detection by unsuspecting prey..

Grazing animals often feed in herds. When a predator attacks, the animals scatter and run in different directions which confuses the predator and allows the animals to escape..

Some animals never venture too far from their home in underground dens or thick vegetation and can quickly hide when danger approaches..

Many animals have keen senses of sight, smell, and hearing so that they can detect danger and escape..

Some animals are active only at night when it is harder for predators to find them..

Trickery can also be used as a formidable defense. False features that appear to be enormous eyes or appendages can serve to discourage potential predators..

Mimicking an animal that is dangerous to a predator is another effective means of avoiding being eaten. .

The final defense is physical or chemical combat. Some animals have horns or antlers to fight off predators. Some animals' physical features make them a very undesirable meal. Porcupines, for example, make it very difficult for predators with their extremely sharp quills. Similarly, predators would have a tough time trying to get to a turtle through its protective shell. Chemical features can be just as effective. We all know the hazards of scaring a skunk! The chemicals released result in a not so pleasant aroma that an attacker will never forget. The dart frog also uses chemicals (poisons secreted from its skin) to deter attackers. Any animals that eat these small frogs are likely to get very sick or die.

Predator Adaptations
Tools of the Trade

Vision
One of the most striking physical traits of many predators is the forward
location of the eyes. This arrangement provides the predator with binocular
vision. Since the field of view of the two eyes overlaps, the brain receives
two images of the same object at one time. This allows the brain to make precise
judgements of depth and distance.

Smell
The sense of smell is of vital importance to many predators. They use it not
only to locate prey, but also to communicate with others of their species.
While mammals smell with their nose, other creatures have different arrangements
- snakes smell with their flickering tongues, and insects smell with their
antennae. Most birds have no sense of smell at all.

Among mammals, an elongated
snout often indicates an increased reliance on the sense of smell. The longer
snout provides more room for complex nasal passages housing chemically sensitive
cells that do the actual smelling. Compare the skull of the bobcat with the
skull of the coyote. The bobcat, like other felines, hunts primarily by sight
and so has a fairly short snout. The coyote, on the other hand, relies heavily
on his long nose to help him find his prey.

Hearing
Most mammalian predators possess a keen sense of hearing. Their external ear
flaps, or pinnae, can be swiveled forward or back to focus on a particular
source of sound. The ears of bats are often highly specialized, with strange
shapes that help catch the echoes of their sonar-like calls as they fly.

Birds also hear extremely
well. Among the most remarkable avian ears are those of the barn owl. Its
ears are not symmetrically placed - one is higher than the other. With its
ears offset in this way, the barn owl can pinpoint the direction from which
a sound is coming. Scientists have shown that barn owls can locate and catch
mice, even when blindfolded!

Some predators do quite
nicely without any sense of hearing at all. Snakes, for example, have no external
ears. They can pick up vibrations through the bones of their lower jaws, but
rely on their other senses - sight, smell, and even heat detection - to find
prey.

Beaks and Feet
Mammals aren't the only animals with adaptations for catching prey. Birds
display a wide variety of physical adaptations that help them obtain food.
These adaptations are most easily observable in birds' beaks and feet.

Long beaks for probing,
hooked beaks for tearing, thick ones for crunching seeds, thin ones for picking
insects - each beak tells a story about its owner. Beaks provide birds with
a lightweight alternative to a mouthful of teeth - like hollow bones, they
are an adaptation for flying.

The legs and feet of
birds also provide clues to their way of life. Long legs generally signify
a wader, while large claws are found on birds of prey. Swimming birds have
either webbed feet, like ducks, or lobed toes, as in coots and grebes. Many
other species also have specializations in the form or arrangement of their
toes.

Jaw Strength
Many predatory mammals use their jaws to seize and subdue their prey. Their
jaw muscles must maximize the leverage and gripping power at the front part
of the jaws. This increased power is provided by a muscle called the temporalis.
The temporalis muscle pulls the lower jaw toward the top of the skull. To
strengthen this connection, predator skulls often bear a central bony ridge
called the sagittal crest. The sagittal crest provides a strong, secure anchor
point for the temporalis muscle.

The power needed to crush
bones is provided by a different muscle, the masseter. The masseter muscle
pulls the lower jaw toward the cheekbone, or zygomatic arch. In predators,
the masseter muscle is usually smaller than the temporalis, suggesting that
it is more important to seize prey than to crush it.

Among plant eaters, the
reverse is often true. The temporalis muscle is generally smaller than the
masseter. Rather than a sagittal crest, there may be an enlargement of the
lower jaw to provide a better anchor for the masseter. This arrangement suggests
that, for the plant-eater, crushing and grinding vegetation is more important
than biting it off the plant.

Predator StrategiesThe method
used by a predator to pursue its prey is determined by many factors, including
the adaptations of the predator, the adaptations of the prey, and the nature
of the habitat in which they live. A technique that works well in one situation
may prove quite ineffective in another. Each strategy has its own inherent risks
and rewards. Consider three commonly employed techniques: the chase, the stalk,
and the ambush.

The Chase
Hawks are among the many predators that catch their prey by chasing it. Chasing
may involve a significant expenditure of both time and effort to make a successful
capture. To be efficient, predators that chase their prey must concentrate
on species that will provide enough nutrition to offset the energy burned
up in capture. Thus the hawk tends to eat more rodents and birds than grasshoppers,
because grasshoppers just don't provide enough food value to justify the effort
it takes to catch them.

The Stalk
Herons employ a different technique. Standing motionless inshallow water or
wading slowly along the shore, the heron patiently searches for prey, which
it captures with a quick lunge of its long, sharp beak. This method doesn't
require much energy; the search time may be great, but the time to catch prey
once it's found is minimal. A stalking predator can afford to choose smaller
prey and still meet its energy requirements.

The Ambush
The alligator prefers to lie in wait until something edible happens by. This
method of hunting requires little effort at all; however, chances for success
are fairly low. The alligator, a reptile and therefore cold-blooded, has minimal
energy requirements; its metabolism is so slow that it can get by with infrequent
meals. Because a successful ambush depends on the predator avoiding detection
until it strikes, most ambush hunters are fairly small.

Camouflage (matching colors or patterns)
Many animals have fur, feather or scale coverings that match the plants, soil or rocks where they live. The tawny fur of lions helps them to hide in the dry, yellow-brown grasslands of the African savannah. Many desert animals have sandy brown coats that help them to blend into their background. Animals that live in rainforests may be green or brown to match the colors of foliage and tree trunks.

Predators Use Lots of Energy
Hunting PreyFor a predator, hunting
down active prey can be an energy-expensive proposition. There's the energy
involved in searching for prey; the energy involved in chasing the prey; and
the energy involved in capturing and killing the prey. That's assuming the prey
is caught - for many predators, the majority of their attempts end in failure.
For the predator to be successful, these energy losses must be repaid by the
energy it gains from its food.

There is another way. Rather
than going through all the trouble of killing something to eat, a meat eater
could simply feed on the carcass of an animal that was already dead. Such behavior,
called scavenging, can provide the benefits of eating meat (high nutrition,
easy digestibility) without many of the associated costs. Indeed, many predators
do not hesitate to take advantage of such opportunities when they occur.

So why don't predators
become full-time scavengers? Probably because there simply aren't enough dead
animals to go around. The odds of an animal finding a carcass every time it's
hungry are fairly small. So, even though predation takes more effort than scavenging,
in the long run, it may provide a more dependable source of energy.

Importance
of the Predator-Prey Relationship
To sum it all up, the predator-prey relationship is important in maintaining
balance among different animal species. Adaptations that are beneficial to prey,
such as chemical and physical defenses, ensure that the species will survive.
At the same time, predators must undergo certain adaptive changes to make finding
and capturing prey less difficult. Without predators, certain species of prey
would drive other species to extinction through competition. Without prey, there
would be no predators. Thus, this relationship is vital to the existence of
life as we know it.